1. Field of the Invention
The present invention relates generally to adjustable support arm assemblies for repositioning items carried at one end in a three dimensional envelope, and more particularly to such assemblies which have the particular application of repositioning a computer monitor to suit the preference of the user.
2. The Prior Art
Computer monitor support arm assemblies are well known accessories for computer systems. An objective of some such assemblies is to support a computer monitor at one end and to provide adjustment means for moving the monitor within a three-dimensional envelope and also to permit tilt adjustment of the monitor about a vertical axis. The arm assemblies are typically used for moving the monitor toward and away from the user, and repositioning the monitor to suit the preference of the user, and freeing up space on the workstation surface.
One such monitor assembly is sold by MicroComputer Accessories Inc. as Product No. 641K. The support arm extends upward from a pivotal base and supports a horizontal beam at a remote end. The beam reciprocally moves back and forth on rollers and includes a plate member at one end for supporting a monitor. In addition, the beam member has a pivoting linkage which adjusts as the support arm is raised and lower to maintain the horizontal beam in a horizontal disposition. Thus the monitor plate can be raised and lowered and rotated 360 degrees by movement of the support arm, and can be adjusted in and out by movement of the horizontal beam.
Other representative assemblies are the MicroComputer Accessories, Inc. Model Nos. 6150 and 6130. The 6150 has a vertical post mounted to a clamp base. The arm has an integral vertical sleeve, and slides down onto the post when the user is assembling the unit. In addition there are three stacking rings which slide down onto the post. The user configures the arm with 0,1,2, or 3 rings under the arm on the post to obtain one of the four height positions. If the arm is placed at any position other than the highest position, the extra rings are slid onto the post above the arm.
The 6130 and 6150 have identical trays attached to the end of the arm. The trays pivot and tilt and there is a slot in the tray similar to that described above for the 641K.
In order to add further adjustability to the assembly, a turntable is mounted on the support plate. The turntable includes a top platform having a semi-spherical center bottom portion, and a stand for supporting the platform. The stand includes a semi-spherical recess in an upper surface for receiving the platform semi-spherical bottom portion, and an aperture extends through the stand bottom to communicate with the stand recess. The platform has an arcuate slot or a series of holes extending through the bottom center portion which aligns with the stand aperture. A lock screw is provided to project upward through the stand aperture and the platform slot (or one of the apertures), and a clamping nut attaches to the lock screw end to hold the assembly together and in a fixed mutual orientation.
The turntable can be adjusted to rotate 360 degrees and/or to tilt forward and backward along the platform slot by loosening the clamping nut, whereby freeing the platform to rotate within the stand recess and to tilt forward and backward. After the desired positioning of the platform has been achieved, the clamping screw is tightened to fix the turntable in its preferred position.
U.S. Pat. No. 5,123,621 teaches a monitor support assembly which includes a pivot axis at the base, a secondary intermediate pivot axis which serves to keep an intermediate arm member level, and a tilting support plate at a remote end of the arm member. The support plate includes a slot adjustment mechanism for tilting the monitor in one direction.
While the aforementioned prior art arm assemblies work well and has been commercially well received, certain shortcomings prevent them from satisfying all of the needs of the market. First, the apparatus are relatively complex, requiring a plurality of pivot adjustment mechanisms to place the monitor in its desired altitude, and rotational and attitudinal positions. The complexity of the arm linkages and associated hardware increases the cost of the assemblies, increases the burden and cost of their manufacture and assembly. Moreover, such assemblies are more complex and time consuming to adjust than desired by the end user.